1. Technical Field
This invention relates generally to sailing yachts, and more particularly to a high performance sailing yacht having a laterally moveable ballast suspended beneath the hull that provides a counter heeling force when the yacht is underway, together with forward and aft foils that provide improved leeway control.
2. Description of Related Art
U.S. Pat. Nos. 5,163,377 and 5,622,130 describe various aspects of a keel-less sailing yacht that has fore and aft cambered foils for leeway control and a dynamic gravitational ballast for heeling resistance. A ballast-supporting structure, in the form of an elongated strut extending downwardly from the hull, supports the ballast generally beneath the hull. Twin fore and aft rotatable foils are also supported by the hull with extension below the hull for optimum performance under a wide range of operating conditions, preferably being controlled by a hydraulic or electric system.
A keel-less sailing yacht with appendages in the form of a movable ballast-supporting strut and twin fore and aft foils is sometimes referred to as a canting ballast twin foil (CBTF) sailing yacht. Such CBTF sailing yachts enjoy recognized sailing success accompanied by significant interest in CBTF technology. However, various structural and operational concerns need attention.
For example, the downwardly depending foils and ballast-supporting strut hinder operations in shallower water. In addition, replacement of foils damaged by vessel grounding is impaired. Furthermore, operating performance of larger sailing yachts, including those designed for ocean racing or cruising, can suffer somewhat under various sailing conditions (e.g., sailing off wind) due to the friction drag introduced by the downwardly depending appendages. Thus, a need exists for CBTF improvements in these respects.